Causes
Boils on the leg belong to the so-called soft tissue infections. Apart from furuncles, other clinical pictures such as carbuncles and folliculitides also belong to the soft tissue infections. A preferred localization of furuncles are the thighs and the intimate and anal areas.
Furuncles develop where hair follicles are located. Especially men, who naturally tend to have more hair, are affected. A boil on the leg is caused by an infection of the hair follicle with bacteria.
The most common pathogen is the bacterium Staphylococcus aureus. More rarely, so-called streptococci are found as triggering pathogens. People who suffer from atopic eczema – also called neurodermatitis – or diabetes mellitus are particularly at risk. Both diseases lead to a weakening of the skin’s immune system, which can lead to an increase in soft tissue infections such as boils. In addition, a warm and humid climate and poor hygiene can promote eczema.
Appearance and symptoms of furuncle
Before the actual furuncle develops, a pus-filled blister or pustule forms in the center of the inflammation. On closer inspection, a small hair can be seen in the middle of the pustule, located in the center of a swelling. (Boils are caused by inflammation of a hair follicle).
When the inflammation then spreads to the adjacent tissue, the actual boil develops, which increases in size during this process. A boil usually has a diameter of half a centimeter to two centimeters. A pressure-sensitive, tightly elastic knot is formed.
In the course of maturation, a purulent melting occurs and in the middle of the knot the tissue dies off, which is called necrosis in technical terms. When the boil finally breaks through the skin, the pus is emptied. A small, retracted scar remains after healing.
If the process is free of complications, boils are usually not accompanied by additional symptoms. In rare cases, slight general symptoms such as increased temperature may occur. The pathogens are surrounded by a kind of capsule within the furuncle, so that they are protected from attacks of the immune system.